I notice when I start DosBox it says at the top that I can change the hue with F11 (or Alt+F11). However, it doesn't say how to enter composite video mode.
Here's a screenshot of when it starts up https://i.imgur.com/HpM2Hl9.png
And yes, I read the readme file, just like that message box says for more info. But even the readme file doesn't tell me how to switch to composite video mode. No mention of key presses or a config file setting. Even the config file itself doesn't appear to have any setting that would enable this mode.

Please tell me how to enter composite video mode for CGA graphics mode.